The present invention relates to a driving device for a cable type window regulator, and more particularly, to a device for actuating cables in a cable type window regulator used for opening/closing a window of an automobile, a building or the like.
As a driving device for a cable type window regulator, there has been hitherto known a device which has a spiral spring (balancing spring) for obtaining a balance between an operational force for lifting a window glass and a force for lowering the window glass (For example, U.S. Pat. Nos. 4,440,354, 4,662,236, 4,628,759. Such spiral spring is, for example as shown in FIG. 10, housed in a casing or housing 51 and is arranged concentrically with a drum 50 for winding and unwinding wires or cables 64, 65.
In such a case, a spiral spring 52 is generally attached to a disk-like rotatable member. Further in the example of FIG. 10, the spiral spring 52 is housed in a cup-like spring case 53, so as to be well protected by the spring case. The outer end and the inner end of the spiral spring 52 are respectively engaged with the inner wall of the spring case 53 and a boss 54 of the housing 51. Then the spiral spring 52 urges the spring case 53 to rotate in the direction of arrow P.
Further, a driving shaft 55 is rotatably supported with the above-mentioned boss 54 and a center hole of a cover or lid 56, and a manually operated crank handle 57 is securely attached to an end of the driving shaft 55. The spring case 53 and the drum 50 are freely rotatably mounted on the driving shaft 55 and are engaged with each other through a set of ring-like ratchet teeth 58, 59.
At the upper end surface of the drum 50, an engaging projection 60 is provided so that the engaging projection 60 can engage with side edges of a fan-like cut-off portion 62 of a flange 61. The flange 61 has a cup-like shape and is fixed to the driving shaft 55.
Between the outer surface of the flange 61 and the inner surface of the lid 56, a known brake spring 63 is inserted.
The first cable 64 and the second cable 65 wrapping the drum 50 are respectively introduced outward through holes 66, 67 formed in the housing 51.
Such driving device is attached to a door panel of an automobile as a part of window regulator, for example, as shown in FIG. 5.
In FIG. 5, numeral 68 denotes a driving device, and the device 68 is fixed to the door panel together with a guide rail 69. On the other hand, a carrier plate 72 is attached to the window glass 71. To the carrier plate 72, the first cable 64 and the second cable 65 extending from the driving device 68 are anchored. As a result, those cables 64, 65 form a closed loop substantially.
In the above-mentioned driving device, when the window glass 71 is descended, the sprial spring 52 is wound up so as to increase the load, and when the window glass is ascended, the rebound force of the sprial spring 52 is utilized to reduce the load, and therefore, operational forces of ascending direction and descending direction are advantageously balanced.
However, in the conventional window regulator, there happens a case that rain drops or the like sticking to the cables are caught with the cables on the drum 50, and the drum 50 and the spiral spring 52 get wet. Then, rusting occurs on the spiral spring 52, and the strength and durability of the spiral spring 52 are lowered. And further, sliding resistance between slidable members becomes large. As a result, the driving device is functionally disordered.
An object of the present invention is to eliminate the above-mentioned problems of the conventional driving device, and to provide a driving device for a cable type window regulator having good rust-durability.
Further, in the conventional driving device, when weight of the window glass is large, a large crank handle 57 should be employed or a small drum should be employed in order to design the operational force within a suitable extent.
However, the effective turning radius of the crank handle is limited from a requirement of operational convenience, and the radius of the drum is limited from the minimum radius of curvature of the wire or cable. Then, the balancing force is insufficient. On the contrary, in such case that the urging force of the spiral spring is intended to enlarge, very large spiral spring 52 and spring case 53 are required. In addition, there is a problem that various sizes of spring case (and therefore, housing) should be prepared in accordance with the weight of window glass.
The second object of the present invention is to eliminate the above-mentioned problems, and to provide a driving device for a window regulator, in which a sufficient balancing force can be obtained for relatively heavy window glass, and a suitable balancing force can be obtained by merely changing a few parts in accordance with the weight of window glass.
Further, there is general antinomic problem in the size of spiral spring. That is to say, even if a large spiral spring can be employed, a spring with large spring-coefficient cannot secure good durability for repeated large torque.
On the contrary, if durability can be secured, a torque sufficient to balance the weight of window glass cannot be obtained.
Therefore, the present invention is also directed to a driving device for a window regulator which achieves both the above-mentioned antinomic properties (high torque and high durability) in a spiral spring, without sizing-up (especially in the direction of thickness of door panel).